1. Field of the Invention
The present invention relates to a vibration isolating apparatus in which a plurality of small liquid chambers are disposed between a vibration generating portion and a vibration receiving portion so as to absorb vibrations by means of flow resistance of a liquid moving between the small liquid chambers.
2. Description of the Related Art
A known vibration isolating apparatus for an engine mount, a carburetor mount, a body mount and so forth for use in automobiles is provided with a liquid chamber part of which is formed of a resilient member (Japanese Patent Laid-Open No. 113835/1985). This liquid chamber is partitioned into a plurality of small liquid chambers by partition walls, and the small liquid chambers communicate with each other through restraining passages. The arrangement is such that vibrations are absorbed by resistance occurring when the liquid in one small liquid chamber passes through the restraining passage and moves to another small liquid chamber at the time of occurrence of the vibrations.
In addition, in this vibration isolating apparatus, when high-frequency vibrations which can clog the restraining passages have occurred, a movable body provided on the partition wall moves by small degrees, with the result that an increase in the internal pressure of the liquid chamber is restrained, thereby absorbing high-frequency vibrations (100-400 Hz) of reverberatory sounds and the like.
With this type of vibration isolating apparatus, however, when low-frequency vibrations (8-15 Hz during engine shaking and 20-40 Hz during idling) occur during engine shaking, idling, or the like, the movable body also moves, with the result that the amount of liquid passing through the restraining passage declines. Consequently, it is impossible to obtain an effective attenuating effect owing to the resistance of the liquid passing through the restraining passages.